This invention relates to optical devices, and more particularly to optical waveguide devices.
In the integrated circuit industry, there is a continuing effort to increase device speed and increase device densities. Optical systems are a technology that promise to increase the speed and current density of the circuits. In long-distance waveguide applications such as fiber optic transmission lines, optical signals can be attenuated differently through different bandwidths of the optical signals. That is, a high-bandwidth portion of the optical signal can be attenuated to a different signal strength than the low-bandwidth portion of the optical signal. Dynamic gain equalizers are devices that equalize the gain for light through the multiple light bandwidths. Dynamic gain equalizers can be formed from multiple passive elements, with each passive element made from glass or clear plastic or alternatively from a semiconductor material, such as silicon.
Dynamic gain equalizers, as with most optical devices, are susceptible to changes in such operating parameters as temperature, device age, device characteristics, device age, device characteristics, contact, pressure, vibration, etc. As such, the various components of the dynamic gain equalizers are typically contained in packaging that maintains the parameters as desired. Providing such packaging is extremely expensive. Even if such packaging is provided, passive dynamic gain equalizers may be exposed to slight condition changes. Passive dynamic gain equalizers perform differently under different conditions. For example, different bandwidths of light will be attenuated to different levels depending on the conditions. If the characteristics of a passive dynamic gain equalizer is altered outside of very close tolerances, then the optical dynamic gain equalizer will not adequately perform its function. In other words, there is no adjustability for passive dynamic gain equalizers.
As such it would be desirable to provide an optical dynamic gain equalizers that can controllably equalize the strengths of multiple bandwidths of light. Additionally, it would be desirable to provide a mechanism to compensate in dynamic gain equalizers for variations in the operating parameters such as temperature and device age.
The present invention is directed to an apparatus and associated method for altering the propagation constant of a region of equalizing propagation constant in an optical waveguide. The method comprising positioning an electrode of a prescribed electrode shape proximate the waveguide. An altered region of equalizing propagation constant is projected into the waveguide that corresponds, in shape, to the prescribed electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of equalizing propagation constant is controlled by varying the voltage.